| 摘要 |
<p>An anchor rod for insertion in a fastening matrix such as a concrete structural element, by means of a hand-held percussion drill, has a smooth mid-section of slightly reduced diameter just below a slightly thickened intermediate collar that separates it from threading at the external end of the rod and has a profiled ridge and groove section at its insertion end which has a lefthand twist for insertion with a righthand rotation, as well as a frustoconical flat tip. The profiled section increases in diameter gradually towards the tip. At least the profiled section is manufactured by cold deformation with flat ridge tops having minutely burred or beaded edges. The method of setting involves the use of a mortar, preferably a synthetic resin two-component mortar, and there are added, either separately or in one of the mortar components, abrasive particles such as quartz sand grains, of a grain size suited to the size of the grooves in the profiled portion of the rod, so that during insertion of the rod in a pre-bore drilled with a drill of a diameter corresponding to the maximum diameter of the anchor rods, an undercutting type of abrasive effect will widen the bore progressively towards the end thereof, this being assisted by an inherent eccentric movement of the rod as it is rotated and chews into the mortar, breaking up in most cases the fragile capsules in which the components are provided to provide further abrasion. The smooth shaft portion between the intermediate collar and the profiled insertion end of the rod may be provided with a release coating to reduce or prevent bonding with the mortar in order to allow stretching this portion of the rod under stress and providing the effect of an expansion bolt, if such an effect is desired. The bonding effect in any case is at a maximum at the inner end of the bore.</p> |
